As an introduction, it is known that the pieces obtained from stacked composite materials, such as those formed of carbon fiber sheets or glass fibers pre-impregnated with resin (“prepreg”), are widely employed in industry, such as in the aeronautics industry components including stringers, stiffeners and structural reinforcements. These components are characterized by their low weight and high mechanical strength (specific resistance).
One of the existing technologies for the continuous formation of composite laminates is based on a system of rollers and mandrel (roll-forming), originally conceived for manufacturing metal sections. Metal rollers press the composite against the surface of the mandrel debulking the composite and giving it the shape of the mandrel. The part obtained is then cured in an autoclave.
U.S. Pat. No. 7,249,943-B2 discloses an apparatus for forming stiffeners and other elements of reinforcement of composites, comprising a base having in its upper part a longitudinal mandrel with the shape to be given to the laminate arranged thereon, as well as one or several rollers assembled in one or several supports, such that the rollers roll over the composite pressing it against the mandrel for forming it and obtaining the composite part with the desired geometry and ready to be cured. The rolling surface of the rollers has a configuration complementary to the cross-section of the mandrel. Although this apparatus allows manufacturing straight structural sections with changes in thickness and bends, it is not capable of manufacturing more complex geometries, such as for example geometries with changes in plane for overcoming obstacles (joggles), twisted geometries, etc.
Furthermore, even for obtaining simple geometric shapes, such as for example components with an omega-shaped cross-section, it is necessary to have several rollers, all provided with their respective pressure adjustment systems, which complicates and makes the structure of such systems more expensive and jeopardizes the quality of the part obtained due to the occurrence of wrinkles when the rollers act on the composite.
The main drawback of these known systems is their inability to form variable section laminates, since these changes of geometry involve changing the rollers.
To overcome these drawbacks it was designed the system described in PCT/EP2011/069330, from the same applicant as this present application, and unpublished at the time of submission of this application.
This document describes the use of a pneumatic cover with pressurized fluid in its interior, which presses the laminate against a mandrel to form it.
Therefore, the purpose of the present invention to improve the system described in PCT/EP2011/069330, providing a series of advantages which will be explaned later.